JPH0512087B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a wire-cut electric discharge machine, and in particular, the present invention relates to an improvement of a wire-cut electric discharge machine, and in particular, the electric discharge machining section that performs electric discharge machining on a metal material to be machined using an electrode wire is immersed in a machining liquid tank. The movable element is equipped with a sacrificial electrode that is suitable and effective for protecting movable elements, such as bearings, from electrolytic corrosion in a feeding mechanism for electrode wires that are immersed together in the same liquid bath. Related to wire cut electric discharge machine.

[Prior art]

In a wire-cut electric discharge machine, an electrode wire is guided from a wire supply reel installed on a column of the machine body to an upper wire guide via an appropriate number of guide rollers, and then the metal material to be machined is subjected to electric discharge machining. Generally, the electrode wire is guided through a processing section to a lower guide, and from there, a suitable wire feeding mechanism is used to transport the used consumable electrode wire to a collection section such as a wire collection box. At this time, in recent wire cut electrical discharge machines, an automatic wire connecting device is installed near the electrical discharge machining section, and when a wire breaks, it is connected immediately and feeding of the electrode wire is restarted, reducing machining interruptions and improving machining efficiency. I am trying to achieve this. Further, the consumable electrode wire that has passed through the electrical discharge machining section is generally transported to the wire recovery section by a wire feeding mechanism using a belt mechanism from the time it passes the lower wire guide. Moreover, in order to increase the machining speed of wire cut electric discharge machining and improve the machining accuracy, a configuration in which the electric discharge machined part is immersed in a machining liquid tank is also widely used. In this case, the machining liquid is generally subjected to an ion exchange treatment and is passed through a filtration mechanism to sufficiently remove the machining powder, and a large amount of water with a specific resistance suitable for the machining is used.

[Problems to be solved]

However, the discharge current supplied to the electrode wire in the electrical discharge machining section is not consumed in the electrical discharge machining section, but also flows to the electrode wire that is sent toward the recovery section, so that this current flows toward the recovery section. It will leak on the road. In particular, if the specific resistance of the machining fluid is low, and therefore the electrical resistance value is small, leakage current will flow to conductive elements, parts, etc. immersed in the machining fluid bath.
This causes so-called electrolytic corrosion in which these are electrically corroded. If the above-mentioned conductive element is a drive pulley, guide pulley, or tension pulley of a belt mechanism that constitutes a wire feeding mechanism, it may cause electrolytic corrosion of the metal bearing (generally a stainless steel bearing) on the pulley shaft. Eventually, these bearings become unable to rotate, which impedes the smooth operation of the belt feed mechanism. In extreme cases, the pulleys that do not rotate generate large frictional resistance between the belt and the belt. Situations may also occur that lead to the vehicle stopping. Therefore, the present invention is intended to prevent such problems from occurring, that is, to protect movable elements immersed in a machining liquid bath from electrolytic corrosion.

[Means of solution and action]

That is, in view of the above-mentioned problems of the invention, in the present invention, the electric discharge machining section is immersed in a machining liquid tank, and the electrode wire is supplied from the upper wire guide side and conveyed by belt to the collection section via the lower guide. In a wire-cut electrical discharge machine, a sacrificial electrode plate is attached to a movable element of a wire feeding mechanism arranged in an electrode wire feeding path in the machining fluid tank, thereby allowing the machining fluid to flow from the electrode wire in the electrode wire feeding path. Provided is a wire-cut electric discharge machine equipped with a sacrificial electrode characterized in that leaking non-machining current is passed through the sacrificial electrode plate and captured, and the sacrificial electrode is sacrificed to electrolytic corrosion by the leaking current. The movable elements of the body of the wire-cut electrical discharge machine are designed to protect them from electrolytic corrosion, and when the electrodes become worn out due to corrosion, a new sacrificial electrode can be installed. Hereinafter, the present invention will be explained in more detail based on examples.

〔Example〕

FIG. 1 is a partial front view showing the main structure of a wire-cut electric discharge machine equipped with a sacrificial electrode according to the present invention, and FIG. 2 is an enlarged cross-sectional view of the sacrificial electrode attachment section taken along the - line in FIG. 1. .

In FIG. 1, a wire cut electric discharge machine 10
In this example, the electrical discharge machining section 12 is immersed below the machining fluid level H inside a machining fluid tank (not shown). In the electrical discharge machining section 12, the metal material W to be machined is fixed and held on a well-known work table (not shown), so that it can be rotated along with the work table in two orthogonal axes, the X-axis direction and the Y-axis direction, in a horizontal plane. It has become possible to move to An upper wire guide 14 is provided above the metal material W to be processed, and
A lower wire guide 16 is provided below.
Then, the electrode wire 18 is connected to the upper wire guide 14.
are supplied from above, and both upper and lower wire guides 14,
16, the metal material W to be processed is configured to pass through the processing section and be transported and collected from below the lower wire guide 16 to a wire collection section by a belt feeding mechanism 24, which will be described later. Note that the lower wire guide 16
is the vertical column 20 of the wire cut electric discharge machine 10
The used consumable electrode wire 18 , that is, the lower wire guide 1 , is held at the tip of a lower arm 22 extending laterally from the lower arm 22 .
A belt mechanism 24 is held for conveying the electrode wire after passing through the electrode wire 6 to a wire collection unit such as a wire collection box (not shown). In addition, the electrical discharge machining power is
Generally, the metal material W to be machined is supplied to the electrode wire 18 via a feeder (not shown) provided at a suitable location in the electrical discharge machining section 12 and maintained at ground potential.
Electric discharge occurs through the machining gap between the two. Furthermore, machining fluid is supplied under pressure to the upper and lower wire guides 14 and 16 to remove machining debris, and FIG. 1 shows a water supply that supplies pressurized machining fluid to the lower wire guide 16. A tube 23 is shown.

Now, the belt mechanism 24 that conveys the electrode wire 18 to the wire collection section is composed of a pair of upper and lower endless running belt devices 24a and 24b. The electrode wire 18 is conveyed by pinching the protruding electrode wire 18.

At this time, the endless running belt devices 24a, 24b
In both of these, endless belts 25a and 25b receive rotational driving force from a drive pulley, and are guided to travel along a desired conveyance trajectory by a large number of large and small guide pulleys and tension pulleys 26 as shown in the figure. It has a unique structure. Each of these guide pulleys 26 is formed as a movable element having a structure in which a pulley body is mounted on a shaft via a rotation bearing as described later. Therefore, when these guide pulleys 26 are located below the water surface H of the machining fluid, and non-machining current leaks through the machining fluid from the consumable electrode wire 18 held between the endless belts 25a and 25b, this leakage current As a result, the metal rotating bearing is subject to electrolytic corrosion, which impedes rotational operation. According to the invention, therefore, the guide pulley, tension pulley 26, which is formed as a movable element, is fitted with a sacrificial electrode 28 which captures the leakage current. In other words, an electrode member made of a highly conductive and relatively inexpensive metal material such as a copper plate is mounted on the pulley shaft, and the non-processing current leaking from the electrode wire 18 is applied to the bearings, etc., which are essential elements of the movable element. Before energizing, these sacrificial electrodes are energized, and only the sacrificial electrodes 28 are sacrificially subjected to electrolytic corrosion, thereby protecting the movable elements from electrolytic corrosion. Of course, if the pulley body is made of metal, electrolytic corrosion of the pulley body can also be prevented.

FIG. 2 shows an example of the detailed structure of the guide pulley and tension pulley 26 provided with the sacrificial electrode 28. That is, the guide pulley and tension pulley 26 have a rotation bearing 32 on the pulley shaft 30,
A pulley main body 34 is rotatably attached via a pulley main body 32, and a pair of disc-shaped metal electrodes are arranged on the pulley shaft 30 on both sides of the pulley main body 34 as sacrificial electrodes 28 via a spacer 36. It has an attached structure. Sacrificial electrode 28
As mentioned above, the nut 38 (an example formed as a cap nut is shown) is formed from an inexpensive metal plate such as a copper plate, and is formed on the male thread formed at the end of the pulley shaft 30. By screwing together,
The structure is such that the sacrificial electrode 28 is held between the sacrificial electrodes 28 and 28, so that when the sacrificial electrodes 28 are worn out due to electrolytic corrosion, a new sacrificial electrode 28 can be attached.

As mentioned above, an example has been described in which the sacrificial electrode 28 is attached to the guide pulley and the tension pulley 26 which are typically provided in the belt mechanism 24 for conveying the electrode wire 18, but of course, the sacrificial electrode 28 is subject to electrolytic corrosion. It goes without saying that sacrificial electrodes may be similarly provided on members and portions where this is not desirable.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, when machining progresses in a wire-cut electrical discharge machine with the electrical discharge machining section immersed in the machining fluid in the machining fluid tank, the The sacrificial electrode protects the electrode wire from energizing the movable element through a liquid with low resistivity and causing undesirable electrolytic corrosion, which hinders the progress of electrical discharge machining. This makes it possible to extend the life of the movable elements in the wire-cut electrical discharge machine, and ultimately to significantly improve the service life of the wire-cut electrical discharge machine.

[Brief explanation of drawings]

FIG. 1 is a partial front view showing the main structure of a wire-cut electrical discharge machine equipped with a sacrificial electrode according to the present invention, and FIG. 2 is an enlarged cross-sectional view of the sacrificial electrode attachment section taken along the line - in FIG. 1. DESCRIPTION OF SYMBOLS 10... Wire cut electrical discharge machine, 12... Electric discharge machining section, 14... Upper wire guide, 16... Lower wire guide, 18... Electrode wire, 24... Belt mechanism, 24a, 24b... Endless running belt device , 26...Guide pulley, tension pulley, 2
8...Sacrificial electrode, W...Metal material to be processed.

Claims (1)

[Scope of Claims] 1. A wire cut electric discharge machine in which the electric discharge machining section is immersed in a machining liquid tank, and the electrode wire is supplied from the upper wire guide side and conveyed by belt to the collection section via the lower guide. By attaching a sacrificial electrode plate to a movable element of a wire feeding mechanism disposed in an electrode wire feeding path in a machining fluid bath, the non-machining current leaking from the electrode wire in the electrode wire feeding path into the machining fluid can be reduced. energize the sacrificial electrode plate,
A wire-cut electrical discharge machine equipped with a sacrificial electrode characterized by a capture feature. 2. The movable element of the wire feeding mechanism is a rotating pulley of a belt feeding mechanism, and the sacrificial electrode is formed by a metal plate mounted on the shaft of the rotating pulley. Wire cut electrical discharge machine with sacrificial electrode.